1. Field of the Invention
This invention relates to motion picture cameras and motion picture projectors in general, and more particularly to film transport apparatus permitting for the motion picture cameras and motion picture projectors provided therewith to use film magazine without imparting residual intermittent and irregular motions to the film as it is intermittently advanced past the film gate and during the time when the intermittently advancing film is stopped. Still more particularly, the invention relates to improvements in the construction of a film channel in the film gate.
2. Description of the Prior Art
Conventional film transport apparatus for motion picture cameras and motion picture projectors may be classified into two main types with respect to the film reel system: the apparatus which transports the film from a supply open reel to a take-up open reel after it is intermittently advanced past the film gate: and the other the apparatus which intermittently transports the film from a supply reel to a take-up reel enclosed in a film magazine. The apparatus of the former type usually employs an intermittent-drive film pull-down claw in combination with a pair of sprockets arranged as intervening the pull-down claw to continuously pull and supply from and to the reel and to form slack loops of so appropriate lengths on both sides of the pull-down claw between the sprockets that allowance is made for the differences in the instantaneous velocities of the film as it passes through these advancing means. So long as the appropriate film length of each of the slack loops is secured, therefore, there is almost no occasion for the film frame in the film gate to undergo flutter or missing.
On the other hand, the apparatus of the latter type cooperating with a film magazine is provided with no sprocket assembly because of the space limitation in making compact the structure of the film magazine. Any type of commercially available film magazine for use in the motion picture cameras of the hand held type is formed mainly with a film guide assembly and supply and take-up reels within a housing. In this case, that portion of the film which is advanced by the intermittent-drive pull-down claw past the film gate is directly wound onto the take-up reel as it is driven for rotation by a take-up reel drive, thereby the intervening film between the film gate and the take-up reel does not sag into a controlled buffer loop so that when the tension exerted on the intervening film by the take-up reel drive varies irregularly, or when it becomes too strong, residual intermittent and irregular motions are imparted into the film during the time when it is advanced past the film gate as well as during the time when the intermittently advancing film is stopped. Such a problem also becomes serious in the open-reel operation when no sprocket assembly is employed.